In accordance with conventional techniques, it is well known that, by using an X-ray CT apparatus, an MRI apparatus, or an ultrasonic apparatus, a tomogram of an object to be examined can be obtained. Also, the volume rendering method, the surface rendering method, the depth method and the like are known methods of constructing a three-dimensional image (3D image) by shading, on a projection plane, a volume image that has been constructed by aligning a plurality of such tomograms.
Incidentally, the volume rendering method is mentioned in the document “Marc Levoy; “Display of Surfaces from Volume Data”, IEEE Computer Graphics & Applications, pp29–37, 1988.”
However, it is substantially impossible to emphasize the display of a particular portion of a 3D image that is constructed by the conventional volume rendering method so as to easily distinguish it from other portions. For example, it has been impossible to emphasize display of a particular lesion area so as to easily find it in a diagnostic examination, or to emphasize display of a stent graft in order to explain to a patient how it has been inserted in a blood vessel during surgery. Even if the particular lesion area or the stent graft is provided with colors, they are not displayed distinctively from other portions.
The object of the present invention is to provide a three-dimensional image display apparatus that can construct and display a three-dimensional image where a particular portion is emphasized in a display by using the volume rendering method.